Summary
I updated the quad matlab model parameter file with SolidWorks estimates of the test mass and PUM rotational inertias. Previously these values were output from a fitting algorithm using the measured resonance frequencies, see log 10089.
The updated parameter files are quadopt_fiber.m (the generic quad file) and h1etmy.m. quadopt_fiber.m is the general quad file, h1etmy.m is specific to H1ETMY. They are currently identical since we have the most measurements from H1ETMY. Both live in this directory
.../SusSVN/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production
Discussion
This update was done because there has been some discussion on the accuracy of the test mass inertias in the model. The solidworks mass values for the test mass and PUM agree with the measured weights to 0.2% and 0.07% respectively. This doesn't tell us the error for the inertias, but since they are small, it is a good sign. Previosuly, the inertias were chosen by the aforementioned fitting algorithm. These had differed from solidworks by 2% in roll (I3x) and yaw (I3z), and 7% in pitch (I3y). Further, Shivaraj pointed out that the pitch inertia from the fit was smaller than the yaw, which can't be true due to the flats on the optic. The assumption is that the solidworks estimates are more accurate.
With the updated inertias on the PUM and test mass, I made a new fit of the model, floating all the d's of each stage, the inertias of the top mass and UIM, the spring stiffnesses, and the vertical stiffness of the fibers. I wouldn’t put too much faith into the accuracy of these values. The best we can do is try to make a model that matches the information we have. If we ever get new or better information (such as good L-P coupling data) we can update the model with that then.
The plots in the first pdf show a comparison of the measured H1ETMY transfer functions to the previous model fit and the new one. They all match pretty well. The new fit appears to match the top mass L to P measurement better.
The plots in the second attached pdf show the ratios of the new fit to the old fit for the damped L to L TFs from all stages to the test mass. The damping loops were imported from those currently running at LHO. These ratios all appear to be within 10% of unity.
For reference, this is a summary of the history of model revisions on the svn:
* generate_QUAD_Model_Production.m
rev 7359: now reads foton files for main chain and reaction damping
rev 7436: Changed hard coded DAMP gains to get the correct values for LHO ETMX specifically.
rev 7508: Restored damping filter choice for P to level 2.1 filters as opposed to Keita's modification. Cleaned up error checking code on foton filter files, and allowed handling of filter archive files and files with the full path.
rev 7639: renaming lho etmy parameter file
rev 7642: Adding custom parameter file for each quad. Each one is a copy of h1etmy at this point, since that one has the most available data.
rev 7646: added ability to read live filters from sites, and ability to load custom parameter files for each suspension
rev 7652: updated to allow damping filters from sites from a specific gps time (in addition to the live reading option)
planned future revision - seismic noise will progate through the damping filters as in real life. i.e the OSEMs are relative sensors and measure the displacement between the cage and the suspension.
* ssmake4pv2eMB5f_fiber.m
no recent (at least 4 years) functional changes have been made to this file.
* quadopt_fiber.m
- rev 2731: name of file changed to quadopt_fiber.m, removing the date to avoid confusion with Mark Barton's Mathametica files.
- rev 6374: updated based on H1ETM fit in 10089.
- rev 7392: updated pend.ln to provide as-built CM heights according to T1500046
- rev 7912: the update described in this log, where the solidworks values for the inertias of the test mass and pum were put into the model, and the model was then refit. Same as h1etmy.m.
* h1etmy.m
- rev 7640: created the H1ETMY parameter file based on the fit discussed in 10089.
- rev 7911: the update described in this log, where the solidworks values for the inertias of the test mass and pum were put into the model, and the model was then refit. Same as quadopt_fiber.m.
ISI Blend status:
I ran BruCo on 10 minutes of data starting at 2015-Dec-29 16:14:47 UTC. The full report is available here:
https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1135440904/
Unfortunately, in the region between 70 and 100 Hz, which seems the one thta got worse, there hardly is coherence with any channel.
At lower frequency, one can find the usual coherence with SRCL/MICH signals, but it seems too low to explain any excess of noise.